J/other/RAA/21.288 Hot emission-line stars in LAMOST DR5 (Shridharan+, 2021)
Discovery of 2716 hot emission-line stars from LAMOST DR5.
Shridharan B., Mathew B., Nidhi S., Anusha R., Arun R., Kartha S.S.,
Bharat Kumar Y.
<Res. Astron. Astrophys., 21, 288 (2021)>
=2021RAA....21..288S 2021RAA....21..288S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, early-type ; Stars, emission ; MK spectral classification ;
Photometry, infrared ; Optical
Keywords: stars: early-type - methods: data analysis - techniques: photometric -
astronomical databases: catalogs
Abstract:
We present a catalog of 3339 hot emission-line stars (ELSs) identified
from 451 695 O, B and A type spectra, provided by LAMOST Data Release
5 (DR5). We developed an automated Python routine that identified 5437
spectra having a peak between 6561 and 6568Å. False detections and
bad spectra were removed, leaving 4138 good emission-line spectra of
3339 unique ELSs. We re-estimated the spectral types of 3307 spectra
as the LAMOST Stellar Parameter Pipeline (LASP) did not provide
accurate spectral types for these emission-line spectra. As Herbig
Ae/Be stars exhibit higher excess in near-infrared and mid-infrared
wavelengths than classical Ae/Be stars, we relied on 2MASS and WISE
photometry to distinguish them. Finally, we report 1089 classical Be,
233 classical Ae and 56 Herbig Ae/Be stars identified from LAMOST DR5.
In addition, 928 B[em]/A[em] stars and 240 CAe/CBe potential
candidates are identified. From our sample of 3339 hot ELSs, 2716 ELSs
identified in this work do not have any record in the SIMBAD database
and they can be considered as new detections. Identification of such a
large homogeneous set of emission-line spectra will help the
community study the emission phenomenon in detail without worrying
about the inherent biases when compiling from various sources.
Description:
We provide a catalog of 3339 hot (O, B and A spectral type) ELSs
identified from LAMOST DR5, of which 2716 are newly reported.
Utilizing an automated Python routine, we identified 5437 spectra with
Hα in emission and visually selected 4138 good quality spectra
for further analysis. We noticed that the spectral type provided by
LAMOST is not accurate, deviating by a few sub-classes in some cases.
It is possible that emission features in the spectra are the reason
for such misclassifications. We re-estimated the spectral types of
3307 O, B and A type spectra by a semi-automated Python routine that
identifies three best template fits to the spectra in the blue region
including higher-order Balmer lines such as Hδ and Hε
and then the best fit of the three templates (giving more importance
to HeI and MgII lines) was selected visually.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 1287 3339 Catalog of hot (O, B and A spectral type) ELSs
identified from LAMOST DR5
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See also:
V/156 : LAMOST DR7 catalogs (Luo+, 2019)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
II/328 : AllWISE Data Release (Cutri+ 2013)
II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 43 A43 --- spName Name of the LAMOST spectra fits file
48- 58 A11 --- Class Classification of the source
60- 69 A10 --- SpType Best-fit spectral type
71- 133 A63 --- forbCom Comments on Forbidden lines by visual check
135- 180 A46 --- HaClass Classification of Halpha profile
182- 224 A43 --- l6300 Presence of [OI] 6300Å (1)
226- 230 A5 --- l6363 Presence of [OI] 6363Å (1)
232- 236 A5 --- l6548 Presence of [NII] 6548Å (1)
238- 242 A5 --- l6584 Presence of [NII] 6584Å (1)
244- 248 A5 --- l6717 Presence of [SII] 6717Å (1)
250- 254 A5 --- l6732 Presence of [SII] 6732Å (1)
256- 281 A26 --- LAMOST LAMOST designation ID,
LAMOST JHHMMSS.ss+DDMMSS.s
283- 292 F10.6 deg RAdeg Right Ascension (J2000)
295- 304 F10.6 deg DEdeg Declination (J2000)
306- 314 A9 --- subClass Spectral type from LAMOST
316- 321 F6.2 --- snru Signal-to-noise ratio in u band
323- 328 F6.2 --- snrg ?=999 Signal-to-noise ratio in g band
330- 335 F6.2 --- snrr ?=999 Signal-to-noise Ratio in r band
339- 344 F6.2 --- snri ?=999 Signal-to-noise Ratio in i band
348- 353 F6.2 --- snrz ?=999 Signal-to-noise Ratio in z band
355- 370 A16 --- 2MASS 2MASS ID (HHMMSSss+DDMMSSs)
372- 377 F6.3 mag Jmag ? 2MASS J magnitude
379- 385 F7.3 mag Hmag ? 2MASS H magnitude
387- 393 F7.3 mag Kmag ? 2MASS K magnitude
395- 401 F7.3 mag e_Jmag ? Error in Jmag
403- 408 F6.3 mag e_Hmag ? Error in Hmag
410- 415 F6.3 mag e_Kmag ? Error in Kmag
417- 421 A5 --- Qfl ? 2MASS JHK photometric quality flag
423- 425 A3 --- Rfl ? 2MASS source of JHK default mag
429 I1 --- Xflg ? 2MASS Extended source contamination flag
431- 449 A19 --- AllWISE AllWISE ID (JHHMMSS.ss+DDMMSS.s)
451- 456 F6.3 mag W1mag ? AllWISE W1 magnitude
458- 464 F7.3 mag W2mag ? AllWISE W2 magnitude
466- 472 F7.3 mag W3mag ? AllWISE W3 magnitude
474- 480 F7.3 mag W4mag ? AllWISE W4 magnitude
482- 487 F6.3 mag e_W1mag ? Error in W1mag
489- 494 F6.3 mag e_W2mag ? Error in W2mag
496- 501 F6.3 mag e_W3mag ? Error in W3mag
503- 508 F6.3 mag e_W4mag ? Error in W4mag
510- 514 A5 --- qph AllWISE photometric quality flag
516- 521 F6.3 mag B-V ? B-V color
523- 528 F6.3 mag e_B-V ? Error in B-V color
530- 536 F7.3 mag Vmag ? APASS V magnitude
538- 544 F7.3 mag e_Vmag ? Error in APASS Vmag
546- 552 F7.3 mag Bmag ? APASS B magnitude
554- 560 F7.3 mag e_Bmag ? Error in APASS Bmag
562- 581 E20.15 --- PS1 ? PANSTARRS ID (objID) (TRONCATED !!!!)
583- 603 E21.15 mag Av ? Extinction in V magnitude
605- 622 F18.15 mag b_Av ? Lower limit of extinction in V magnitude
624- 641 F18.15 mag B_Av ? Upper limit of extinction in V magnitude
643- 660 F18.15 mag n(J-K) ? (J-K) lada index (2)
662- 679 F18.15 mag n(K-W2) ? (K-W2) lada index (2)
681- 702 E22.15 mag (J-H)0 ? Extinction corrected (J-H) color
704- 725 E22.15 mag (H-K)0 ? Extinction corrected (H-K) color
727- 744 F18.15 mag (W1-W2)0 ? Extinction corrected (W1-W2) color
746- 763 F18.15 mag (W2-W3)0 ? Dextinction corrected (W2-W3) color
765- 782 F18.15 mag e_(J-H)0 ? Error in extinction corrected (J-H) color
784- 801 F18.15 mag e_(H-K)0 ? Error in extinction corrected (H-K) color
803- 823 E21.15 mag (BP-RP)0 ? Extinction corrected (BP-RP) color
825- 842 F18.15 mag VMAG ? Absolute APASS V mag
844- 864 E21.14 mag B_VMAG ? Upper limit of Absolute APASS V mag
866- 883 F18.15 mag b_VMAG ? Lower limit of Absolute APASS V mag
885- 902 F18.15 mag E_VMAG ? Error in upper limit of Absolute
APASS V mag
904- 921 F18.15 mag e_VMAG ? Error in lower limit of Absolute
APASS V mag
923- 933 A11 --- Name-our ? Name assigned
941- 949 A9 --- Name-uniq Unique Name assigned after considering
duplicates (LEMC NNNN)
951- 971 E21.15 --- GaiaDR3 ? Gaia Source ID (TRONCATED !!!)
973- 993 E21.11 deg RAGdeg ? Gaia Right Ascension (ICRS) at Ep=2016.0
995-1000 F6.4 mas e_RAGdeg ? Error in Gaia Right Ascension
1002-1016 F15.11 deg DEGdeg ? Gaia Declination (ICRS) at Ep=2016.0
1018-1023 F6.4 mas e_DEGdeg ? Error in Gaia Declination
1025-1031 F7.4 mas Plx ? Gaia Parallax
1033-1039 F7.4 mas e_Plx ? Error in Gaia Parallax
1041-1049 F9.4 --- RPlx ? Gaia parallax divided by error in
parallax
1051-1058 F8.4 mas/yr PM ? Gaia total proper motion
1060-1066 F7.3 mas/yr pmRA ? Gaia Proper motion in RA
1068-1073 F6.3 mas/yr e_pmRA ? Error in Gaia Proper motion in RA
1075-1081 F7.3 mas/yr pmDE ? Gaia Proper motion in Dec
1083-1088 F6.3 mas/yr e_pmDE ? Error in Gaia Proper motion in
Declination
1090-1096 F7.3 --- ruwe ? Gaia RUWE
1098-1102 A5 --- Dup ? Gaia Duplicated source flag
1104-1112 F9.6 mag Gmag ? Gaia G magnitude
1114-1123 F10.6 mag BPmag ? Gaia BP magnitude
1125-1134 F10.6 mag RPmag ? Gaia RP magnitude
1136-1145 F10.6 mag E(BP/RP) ? Gaia BP/RP excess
1147-1155 F9.6 mag BP-RP ? Gaia (BP-RP) colour
1157-1165 F9.6 mag e_Gmag ? Error in Gaia G magnitude
1167-1175 F9.6 mag e_BPmag ? Error in Gaia BP magnitude
1177-1185 F9.6 mag e_RPmag ? Error in Gaia RP magnitude
1187-1199 F13.6 pc rgeo ? Gaia median geometric distance
1201-1212 F12.5 pc b_rgeo ? Gaia lower geometric distance limit
1214-1225 F12.5 pc B_rgeo ? Gaia upper geometric distance limit
1227-1238 F12.5 pc rpgeo ? Gaia median photo-geometric distance
1240-1251 F12.5 pc b_rpgeo ? Gaia lower photo-geometric distance limit
1253-1264 F12.5 pc B_rpgeo ? Gaia upper photo-geometric distance limit
1266-1287 E22.15 mag (B-V)0 ? Extinction corrected APASS (B-V) color
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Note (1): "yes" or "no", based on an automated line finder routine.
To distinguish forbidden lines from noisy features in low-SNR spectra, we
used the 'prominence' feature in the 'find_peaks' module. We flagged a
forbidden line as "yes" only if the prominence is greater than 0.2;
if the prominence value is between 0.1 and 0.2, it is flagged as "maybe"
since it can be difficult to distinguish it from a noise feature if SNR is
low and if prominence value is less than 0.1, the line is flagged as "no".
As CBeAe stars do not show forbidden lines such as [SII]6717,6731,
[NII]6548,6584 and [OI]6300,6363 in their spectra, it is necessary to
identify and remove spectra with the above mentioned forbidden lines.
Note (2): Lada indices calculated as
nl1-l2=[log(l2Fl2.l1Fl1)]/log(l2/l1), where Fl1 and Fl2
correspond to the extinction corrected absolute flux measured at
l1 and l2 wavelengths (l for λ).
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Acknowledgements:
Baskaran Shridharan, shridharan.1997(at)gmail.com
(End) Patricia Vannier [CDS] 21-Aug-2024